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[textfile] inconsistency: drops consecutive spaces when reading from disk #738

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EsGeh opened this issue Sep 3, 2019 · 4 comments

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@EsGeh
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@EsGeh EsGeh commented Sep 3, 2019

pd version: 0.50.0
Problem: [textfile] obj drops spaces when reading a file.

Example:

[set 1 \ 3, write /tmp/temp, bang(
|
|    [read /tmp/temp, rewind, bang(
|   /
| /
[textfile]
|
[print]

(This patch tries to write and read a message containing 2 consecutive spaces to/from disk.)

  • Expected behaviour:
    Hitting the 1. msg. box (sets the textfile and then writes the content to a temporary file) should output

    1  3
    

    (2 spaces between)).

    Hitting the 2. msg. box reads from the temporary file and should output

    1  3
    

    (with 2 consecutive spaces between) too.

  • Actual behaviour:
    Hitting 1. msg box behaves as expected and outputs:

    1  3
    

    (2 spaces between)).
    Hitting 2. msg box outputs

    1 3
    

    with just 1 space between.

Why this is bad:
Consecutive spaces carry important information.
In many contexts in pd they are used to represent empty symbols. This might be a bit awkward, but works, since pd in most contexts is consistent in this.
For example, this patch creates a list of 3 elements, where the second one is an empty symbol.

              [loadbang]
              |
(bang)        [symbol]
|                |
_         _      _       _
[pack     1      s       3]
|
[print]

One might want to write and read such lists to and from disks. With the current state of [textfile] (and probably also [text]), this wont work without additional hacks.

@EsGeh EsGeh changed the title [textfile] inconsistency: drops multiple spaces when reading from disk [textfile] inconsistency: drops consecutive spaces when reading from disk Sep 3, 2019
@umlaeute

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@umlaeute umlaeute commented Sep 4, 2019

it's consistent with how Pd reads data into binbufs (e.g. how a patch-file is read).

@EsGeh

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@EsGeh EsGeh commented Sep 4, 2019

But do you see the problem?
Dealing with lists that contain empty symbols works fine everywhere in a patch during runtime.
Only wanting to write/read them to/from disk doesn't work.
I can imagine that the current behavior is part of the fundamental conceptual basis of pd.
From a practical side it appears as an inconsistency.
In my pd external I have tools manage state of instruments, also saving them to/from disk. But even in a very simple scenario where someone stores lists on disk can turn problematic.
A list containing empty symbols stored and reloaded from disk even drops entries in the sense of [list length] returning less than before loading!

Is there a chance to change the behavior into not dropping consecutive spaces?
Are there good reasons not to?
Would it break something?

@Spacechild1

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@Spacechild1 Spacechild1 commented Sep 4, 2019

Generally it's possible to escape Pd's special characters with a backslash, e.g. \, \; or \$. I think this should be also possible with whitespace.

In the meantime: if you want to preserve a symbol as is, read/write it as a list of ASCII characters with [list fromsymbol] / [list tosymbol]

@umlaeute

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@umlaeute umlaeute commented Sep 5, 2019

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